Nitrogenous material fractions obtained from gilsonite in froth flotation



United States Patent 3,414,128 NITROGENOUS MATERIAL FRACTIONS OBTAINEDFROM GILSONITE IN FROTH FLOTATION Robert E. Baarson, La Grange, andCharles L. Ray, Wheaton, Ill., assignors, by mesne assignments, toArmour Industrial Chemical Company, a corporation of Delaware N0Drawing. Filed Sept. 24, 1965, Ser. No. 490,114 6 Claims. (Cl. 209-167)ABSTRACT OF THE DISCLOSURE A recovery of molybdenum or molybdenum andcopper from metallic sulfide ores is brought about in a flotationoperation in which finely-divided metallic sulfide ores containingmolybdenum and iron or molybdenum, copper and iron are conditioned witha mixture of heterocyclic nitrogen compounds extracted from the mineralgilsonite and having an average boiling point within the range of about200 F. to 750 F., the molybdenum or molybdenum and copper beingseparated as froth product.

This invention relates to nitrogenous material fractions obtained fromgilsonite in froth flotation, and more particularly to the use of suchmaterial as a collector or auxiliary collector for molybdenum and copperconcentrates from metallic sulfide ores.

An object of the invention is to provide new collectors and combinationsof collectors for the treatment of metallic sulfide ores containingmolybdenum minerals and ores containing copper, molybdenum and ironminerals, and like ores. A further object is to provide a process forutilizing, in the collection of molybdenum and copper concentrates frommetallic sulfide ores, nitrogenous material obtained from gilsonite usedeither alone or in combination with other collectors. A still furtherobject is to provide for the use of synergistic combinations of suchnitrogenous material with other collectors for the collection ofmolybdenum and copper concentrates and for the separation of saidconcentrates. Other specific objects and advantages will appear as thespecification proceeds.

In one embodiment of our invention, nitrogenous material fractionsobtained from gilsonite are employed to condition a molybdenum-bearingsulfide pulp together with a frother, if desired, such as methyl amylalcohol or propylene glycol ether, and following the conditioning,flotation is conducted in the usual manner to effect concentration andrecovery of the molybdenum concentrate. We have discovered that suchnitrogenous material is particularly effective as a collector formolybdenum concentrates from metallic sulfide ores.

In the foregoing specific embodiment, metallic sulfide ore containingpredominantly molybdenum is ground to a finely-divided state and a Waterpulp of the finelydivided ore is mixed or conditioned with about 0.03lb. of the collector and about 0.03 lb. of a frother per ton of dry ore.Following conditioning, flotation is conducted for several minutes. Anadditional amount of collector and frother may then be added andflotation continued for another period. The flotation concentrate thusobtained may then be subjected to further upgrading operations in orderto produce a concentrate of higher grade. The quantities of collectorrequired may range from about 0.005 lb. to about 0.5 lb. per ton of dryore, but such range of quantities may vary beyond the above range,depending upon the nature of the ore treated.

Where the metallic sulfide ore contains substantial amounts of copper inaddition to molybdenum, we prefer to employ with the nitrogenousmaterial fractions obtained from gilsonite a cooperating collector forsimultaneous recovery of copper and molybdenum concentrates, and suchconcentrates may be separated by depressing the copper concentratethrough the use of heat or depressant materials such as Nokes reagent,sodium hydroxidje,

potassium permanganate, sodium sulfide, sodium ferrocyanide, etc.

The nitrogenous material is derived from mineral gilsonite throughdistillation, acid extraction, and Well known extraction techniques.Such crude mixed heterocyclic nitrogenous material occurs as aby-product in the manufacture of petroleum products from the gilsonitemineral by the American Gilsonite Company. The extreme complexity of themixture of ditferent compounds in the crude material renders a completequalitative analysis substantially prohibitive.

The American Gilsonite Company has assigned descriptive nomenclature tovarious fractions of this type material as follows:

(1) Light Bases from HBF.Extracted from a naphtha stream ofapproximately 283 F. volumetric average boiling point and 222 F. to 400F. boiling range.

(2) Intermediate Bases From PPR-Extracted from a heavy naphtha stream ofapproximately 422 F. volumetric boiling point and 400 to 590 F. boilingrange.

3) Medium Bases from LGO.-Extracted from a gasoil stream of about 520 F.volumetric average boiling point and 460 to 665 F. boiling range.

(4) Semi-purified Acid Extracted Nitrogen Compounds:

(a) Nitrogen Bases I.Boiling range 491 F. to 509 F.

at 760 mm.

(b) Nitrogen Bases II.-Boiling range 610 F. to 641 F. at 760 mm.

(c) Nitrogen Compounds III.-Boiling range 700 to 710 F. at 760 mm.

(d) Nitrogen Compounds IV.Boiling range 745 to 755 F. at 760 mm.

(e) Bottoms V.--Boiling range 755 F. and higher at (5) NitrogenDistillate.-A crude mixture of nitrogen bases obtained by distillationand representative of 4(a) through 4(c) inclusive as above, plus somenon-nitrogenous compounds.

(6) Nitrogen Bases Concentrate Oil.An extracted mixture of cyclictertiary amines plus some non-basic nitrogen compounds.

(7) Pyrrole Polymer Oil.An extracted mixture containing predominantlynon-basic nitrogen compounds and some cyclic basic nitrogen compounds.

In the practice of the present invention, all of the foregoing fractionswhich have a boiling range of about 200 to about 700 F., and preferablythose having an average boiling point within the range of about 450 to750 B, may be employed. Best results, however, have been obtainedthrough the use of fraction 6 in the above descriptive outline, namely,nitrogen bases concentrate oil, and fraction 5, nitrogen distillate. Bythe use of nitrogen bases concentrate oil, which is referred to in thetrade and herein as NBC oil or Gilsamine, we have obtained excellentresults in recovering molybdenum concentrate from metallic sulfide oresin which molybdenum is the principal metal to be recovered. Similarly,excellent results have been obtained by the use of nitrogen distillate(fraction 5). Where the metallic sulfide ores contain copper as well asmolybdenum, We find that the NBC oil and nitrogen distillate are highlyeffective as auxiliary collectors in the recovery of both molybdenumfractions and copper concentrates. By the term nitrogenous materialobtained from gilsonite, we intend to include fractions 1 to 7,inelusive, in the above-mentioned nomenclature of the American GilsoniteCompany, and by the term nitrogen bases concentrate oil, or NBC oil, weintend to include fraction 6 as described in such nomenclature. Asstated above, the term nitrogen bases concentrate oil or NBC oil is aterm commonly used in the industry and is understood as defining aspecific material. Also, the term nitrogen distillate is commonly usedin the industry and is understood to designate fraction 5 as describedin the above descriptive nomenclature.

While NBC oil is regarded in the trade generally as a waste material, wehave found it particularly useful and effective as a collector when usedalone in the conditioning of metallic sulfide ores containingpredominantly molybdenum. Where the ore contains substantial amounts ofcopper which must be recovered, we prefer to employ the NBC oil togetherwith known collectors such as sodium and potassium xanthate having 2 to12 carbon atoms, isopropyl ethyl thionoca-rbamate, alkyl or aryldithiophosphate, etc. In the case of a copper-bearing mineral in whichthere is very little molybdenum, the use of the NBC oil aids in therecovery of copper when used in conjunction with the commonly usedcollectors for copper. Further, it materially aids in the depression ofiron pyrite and prevents excessive recovery of this mineral.

We have also discovered that the use of NBC oil with S-substitutedisothiouronium salts provides an unusually effective combination ofcollectors for the recovery of molybdenum and copper concentrates frommetallic sulfide ores containing these minerals along with ironminerals. S-substituted isothiouronium salts are preferably prepared byrefluxing an alcoholic solution of thiourea with a fatty halide or withan aromatic halide and are represented by the following formula:

where R is an aliphatic (straight chain or branched chain),cycloaliphatic, or aromatic hydrocarbon group having 2 or more but notmore than 24 carbon atoms and preferably not more than 8 carbon atoms,or mixtures thereof, and where X is a halide such as Cl, Br, I, etc.Best results have been obtained when the hydrocarbon group has from 4 tocarbon atoms. Other methods of preparation of the collectors may beemployed.

Specific examples of the collectors may be designated as benzyl-, ethyl,isopropyl-, n-butyl-, n-amyl-, isoamyl-, 2-ethylhexyl-, n-octyl-,1-methyloctyl-, dodecyl-, lauryl-, tetradecyl-, and tallowisothiouronium chloride, and other salts as defined above where thefatty halide or aromatic Cir halide has from 2 to 24 or, preferably,from 2 to 18 carbon atoms and including mixtures of said halides. Thepreferred collectors have from 4 to 10 carbon atoms in the collectormolecules and include n-butyl isothiouronium chloride, n-amylisothiouronium chloride, and 2-ethylhexyl isothiouronium chloride.

Since the collectors are either water-soluble or water dispersible, itis preferred to apply them to flotation as water solutions or waterdispersions ranging from about 1% to about 10% active by weight.

Unusually good results have been obtained when the S-substitutedisothiouronium salts are employed with NBC oil and also with a knownclass of collectors which are referred to as sulfhydryl" collectors,which include the alkyl or aryl dithiophosphates, dithiocarbonates(xanthates), dithiocarbamates, thionocarbamates, thioureas, xanthogenformates, and the like, commonly used for flotation treatment ofmetallic sulfide ores.

As specific examples, NBC oil has been employed effectively with n-butylisothiouronium chloride and with n-amyl isothiouronium chloride and2-ethylhexyl isothiouronium chloride. Where considerable copper isinvolved, we prefer to add to each of the combinations above isopropylethyl thionocarbamate or sodium or potassium xanthate having from 2 to12 carbon atoms. Another effective combination has been NBC oil togetherwith alkyl dithiophosphate and isopropyl ethyl thionocarbamate.

The proportions of NBC oil to the other collector or collectors may bevaried substantially, but for the recovery of copper alone, we prefer touse the proportions of 1:2 to 2:1. A 1:1 ratio has been found verysatisfactory. Where both copper and molybdenum are to be recovered, asatisfactory proportion of the NBC oil to the other collector orcollectors is 1:2 to 2:1, the preferred proportion being 2:3.

After the collection of molybdenum and copper concentrates, any of thecommonly-used agents may be employed for the copper-depressing step. Forexample, Nokes reagent (2. reaction product of a material such as sodiumhydroxide with a material such as phosphorus pentasulfide) may be used.A combination of heat and an excess of either lime or sodium hydroxidemay be employed. Sodium sulfide, or sodium ferrocyanide, or variouscombinations of the foregoing agents may be employed. We have found thatferrocyanide is particularly useful as a copperdepressing agent when thecollectors described above are employed.

The invention may be further illustrated by the following examples,which are illustrative of preferred embodiments of the invention, butthe invention is not limited thereby.

EXAMPLE I A South American ore analyzing 2.8% copper and 0.72%molybdenum was crushed and ground in a laboratory rod mill to pass 96%through 48 mesh. The 48 mesh 200 mesh fraction was 60% by weight of thetotal product; the remainder 200 mesh. The product was ground at 50%solids and a 0.01 #/T addition of a collector was added to the mill.Some of the tests were conducted at a pH of 11.5 using lime, and othertests as indicated were conducted at a natural pH 7.5.

The ground pulp was diluted to 20% solids in a 500 gram Denver flotationcell, conditioned for 10 sec. with Dowfroth 250, and floated for 2minutes. After the preliminary flotation, additional flotation stepspreceded by small collector additions and conditioning in the cell weremade until froths were barren of sulfide minerals. The concentrates werefiltered, dried and assayed. The tests were conducted on severaldifferent ore samples as indicated in the folio wing Table I.

TABLE I Rougher Conc. Rougher Tail Rougher Recovery Reagent and Test No.#lT pH Percent Percent Percent Percent Percent Percent Cu 1 Cu Mo Cu 1 0South American Ore #12.8% Cu; 0.72% Mo:

Nitrogen Distillate (#485-117) .115 7. 5 19. 62 5. 21 0. 174 0.0444 94.894. 4 Nitrogen Distillate (#485335) 0. 138 7. 7 18. 18 4. 49 0. 1660.0499 95. 0 93. 9 51 ltrogen Dlstillate (#485-118). 11. 2 13. 85 7.26 1. 65 0.0428 45.1 94. 3 gg fi'iig 040 7.8 16. 33 3. 92 0.096 0.06097. 2 93. 0

ar 2 1i(#4st bb5IIIIIII III1IIIIIII' 5: 33} 11 55 76 69 Q 091 M90 910 1South American Ore #2, Ore Analysis-1.20% Cu; 1.16% M0; 8.9% Fe:

Nitrogen Distillate (#502-16) 0.168 11. 2 3.17 8. 73 0.87 0.098 32.4 92.2 NBC Oil (#502-17 0. 168 11. 2 4. 26 6. 54 0. 68 0. 103 56. 9 93. 0Nitrogen Distillate (#5023) 0. 150 7. 3 3. 56 10. 25 0. 93 0. 094 29. 492. 2 NB Oil #502-11 0. 150 7. 3 4. 41 6. 24 0. 58 0. 161 60. 0 88. 5 gj(3,5252 8: 11. 5 4.15 a. 34 0.151 0. 492 90.2 68.7

0.03 N-bntylisothiouronium Chloride (#50236) o. 04} 6 27 1127 4 4Canadian Molybdenum Ore- 0.097% Mo; 2.13% Fe:

N 22) 0. 075 7. 4 9. 70 0. 025 91. 8 Mineral Seal Oil (39) 0. 06 8. 1 8.44 024 91. 2

In the above, nitrogen distillate is used alone as a col- EXAMPLE II lifa g 3 f gg g qgb i fifi The ore used in both parts of Table II wasprepared i s 32 21 2 553 g g in the same manner as that outlined in theprocedure g 2 S 5. t st we conducte' at two for Table I. Analyses of thesamples are given separately 1 r g n S l e e 5 re under Table IIresults.

TABLE II Rougher Cone. Rougher Tails Rougher Recovery Reagent and TestNo. #lT pH Percent Percent Percent Percent Percent Percent Cu Mo 0 Cu MoSouth American Ore #1 (Same as Ex. #1) 2.80% Cu, 0.72 Mo:

Nitrogen Distillate 0 092 different pHs and as far as bulk flotation wasconcerned at the neutral pH of 7 .57.7 the nitrogen distillate floatedboth the sulfide and molybdenum minerals almost completely. At a pH of11.2 (the commonly used pH in commercial operations), the copperminerals were depressed and a higher recovery of molybdenum minerals wasobtained which is a desirable trend where separation of the two mineralsmay be required later in steps. It will also be noted that with astandard collector system, Z-ll and Z-200 at the operating pH of11.0-11.5, the molybdenum is not floated as effectively as with thenitrogen distillate.

The second part of the example records the comparison of nitrogendistillate and NBC oil as collectors. The nitrogen distillate was anearly fraction considered semicommercial and later replaced by NBC oil.NBC oil not only replaces the nitrogen distillate, but is favored.

The third part of the example records the eifectiveness of NBC oil at aneutral operating pH against a standard oil used in the field on astraight molybdenum ore.

The last two examples emphasize the efiectiveness of NBC oil alone asregards recovery on ores containing predominately molybdenum sulfide andlittle copper sulfide minerals, or straight molybdenum ores.

Nitrogen distillate and NBC oil are believed to be replacements for eachother and either can be used.

The purpose of this example-was to observe the effectiveness of nitrogendistillate and NBC oil and commonly used sulphydryl collectors on twodifferent ores. It will be noted that in every case where nitrogendistillate and NBC oil was used the sulphydryl collectors against thestandard collectors there is a considerable improvement in themolybdenum recovery and noted improvement in copper sulfide recovery atthis normal pH for commercial operations. This shows synergism; in fact,the recovery of molybdenum is very markedly improved With the additionof nitrogen distillate or NBC oil to sulphydryl-type collectors.

Example III Two different ore samples were treated in the example shownin Table III. The ore designated as Ore No. 3 was an ore fromsouthwestern United States, with an analysis of 0.81% copper and 0.012%molybdenum sulfide. The ore was crushed to pass through a 65 mesh screenretaining 40% on the +200 mesh screen. The ore samples were ground at50% solids with 0.025 #/T of the collector selected and with sufficientlime to give a pulp pH of 10.5. This was followed by a 5-minuteflotation time and 20-second conditioning time, with cresylic acid usedas a frother.

TABLE III Rougher Cone. Rougher Tails Rougher Recovery Reagent #/I pHPercent Percent Percent Percent Percent Percent Cu M Cu Mo Cu MosoutNhgccstgrrli U.S. Ore #30.Sl% Cu, 0.012% M082: 0 7

I 1 1 1 1 1 1 mncnyohslothiouromum chloride 6 7 11.5 8.0 0.086 0.1530.0018 82.3 80.8 N i n-Butylisothiouronium chloride. 0.025 1L6 (10650'170 Q0024 7 7 Sodium Aeroflote (Standard Reagent) 0. 09 10. 6 14.80.088 0.23 0. 0043 73. 0 47.3 South American Ore #21.20% Cu, 1.16% Mo.8.97% Fe: r

0. 056 Z-ethylhcxyl isothiouroniuin chloride (#502 0. 06 112 0m;

Standard:

The ore designated as Ore No. 2 is the same as that tests. The purposeof the testing was to determine the defined in Example 1. effect ofdepression of iron sulfide.

TABLE V Percent Recovery Roughcr Cone. Roughcr Tail of Cu and Fe inReagent and Test No. #/1 pH Concentrate Percent Percent Percent PercentPercent Percent Cu Fe u e u Fe 6. 58 29. 03 0. 198 0. 870 89. 74 89. 74Z-11 and Nitrogen 0. 03 DiStiuate(#488 l9) (L03 10.2 7.10 19.80 0.1483.37 90.24 57.51

This example shows the effective combinations of NBC oil with theisothiouronium salts indicated against the standard reagents on twodifferent ores against two different current standard anioniccollectors. In every case there is improvement in recovery of bothcopper and molybdenum when using the combination over that in using thestandard collectors. The improvement in recovery of molybdenum mineralsis especially noted.

In comparing the results of NBC oil and Z-11 combination of Table IIwith the NBC oil-isothiouronium chloride salts of the second part ofTable III, the improvement of using isothiouronium chloride with NBC oilcan be noted over using current collectors with NBC oil.

EXAMPLE IV Samples of an ore feed of 1.63% Cu and 0.028% M0 were takenfrom the prepared feed to a South American flotation plant and subjectedto laboratory flotation tests.

The effect of depression of iron and improvement in copper recovery isnoted.

EXAMPLE VI A laboratory flotation test was made of a South Americanmetallic sulfide ore containing molybdenum and copper and iron (2.8% Cu,072% Mo), using on the same ore a number of different collectors in aseries of seven tests. The term nitrogen distillate indicates agilsonite distillate corresponding to group 5 in the American GilsoniteCompany nomenclature. The Xanthate is sodium isopropyl xanthate (Z-l 1).The thionocarbamate is isopropyl ethyl thionocarbamate (L200)- Inaccordance with the test procedure, the grind was at 50% solids and theamount of collector added to the mill varied with the collectors tested.The bulk flotation pH level varied between 7.6 and 11.6. The groundpulps were diluted to about solids in a 1,0'00-gram stainless steelDenver flotation cell (1800 r.p.m.), conditioned for TABLE IV RougherCone. Rougher Tails Rougher Recovery Test No. Reagent #/1 pH PercentPercent Percent Percent Percent Percent Cu M0 Cu Mo Cu Mo 1N-butylisothiourouium chloride 0. 0% 11.5 27.5 0.20 0.16 0.010 90. 5 47.3 2 {g ff ffffffff{ f{fE fff 8: S 11. 5 29.6 0. 21 0.16 0. on 91. 0 51.5 3 Z-ll 0.04 11.5 28.4 0.20 0.16 0.019 90.5 36.2

N -butylisothiouronium Ol1l01Id0 0.02 4 NBC Oil 0.097 11.5 25.6 0.200.16 0.016 91.0 44.0 0. 0.

This example shows the effect of NBC oil on recovery of molybdenum usinga standard collector such as Z-ll, the N-butylisothiouroniurn chloride,and in combination with the referenced collectors. The addition of NBCoil with an isothiouronium chloride salt give an improvement of 15% inrecovery over the results obtained with the standard reagent Z-ll, ofwhich 4.2% can be attributed directly to the NBC oil. The NBC oil isalso compatible with combinations of the isothiouronium salt (acationic) and the Z11 (an anionic), giving 8% improvement over theresults obtained by the standard Z-ll.

EXAMPLE V seconds (60 seconds if the collector was added to theflotation cell) with Dowfroth 250 and floated 5 minutes.

An additional flotation step, preceded by a collector addition andconditioning in the cell, was made for 3 minutes. The two rougherconcentrates were combined and thickened. The thickened bulk concentratewas then reground in a ball mill for '5 minutes at approximately solids.A minimum pH level of 11.9 was used in a cleaner flotation step. Thereground pulps were diluted to about 20% solids in a 250-gram stainlesssteel Denver flotation cell (1200 rpm.) conditioned 15 seconds (1minute, if additional collector was added to the cell) and floated 3minutes, constituting the first cleaner flotation step. A second cleanerflotation product was collected for 2 minutes after another 15 secondconditioning period.

The two cleaner products were combined as a bulk cleaner concentrate.

The bulk cleaner concentrates of copper and molybdenum obtained asdescribed above were dewatered, and were subjected to a flotationprocess for the separation of molybdenum minerals from copper minerals,using various depressing agents for copper minerals in accordance withthe following procedure.

The thickened copper-molybdenum bulk cleaner concentrate was subjectedto the particular depressant system being tested by conditioning in astainless steel beaker with an air-driven mixer. The conditioned pulpswere .then diluted in a ZSO-gram stainless steel Denver flotation cell(1200 rpm), pH adjusted to 7.0 7.3 (except when the sodium sulfidedepressant system was used, in which case thepH level was near 12.0),conditioned for 2 minutes and floated 4 minutes.

The rougher Mo concentrate thus obtained was then subjected to a secondaddition of the depressant system being tested. The conditioned pulp wasthen diluted to flotation density in a 250-gram stainless steel Denverflotation cell (1,000 rpm), pH adjusted to 7.0-7.3, conditioned for 1minute and floated for 3 minutes, the froth product from this stepconstituting the molybdenum concentrate. Test results are shown in TableVI.

We claim:

1. In a process for the separation of molybdenum in metallic sulfideores containing molybdenum and iron minerals, the steps of conditioninga water suspension of said ores in finely-divided condition with amixture of heterocyclic nitrogen compounds extracted from the mineralgilsonite and having an average boiling point within the range of about200 F. to 750 F., and separating molybdenum concentrate as frothproduct.

2. The process of claim 1 in which the heterocyclic nitrogen compoundsare selected from the group consisting of nitrogen distillate andnitrogen bases concentrate oil.

3. The process of claim 2 in which the amount of the compound is about0.005 to about 0.5 pound per ton of dry ore.

4. The process of claim 1 in which said metallic sulfide ores containmolybdenum, copper and iron, and molybdenum and copper concentrates areseparated as froth product.

5. In a process for the separation of molybdenum and copper in metallicsulfide ores containing as metallic constituents molybdenum, copper andiron and in which said ores are finely ground and suspended in watercontaining lime, the steps of conditioning said ore with a mixture ofTABLE VI T t Rougher Couc. Percent Distribution of Metals es No.Collector Used #/1 pH 0 M Agent used {or depressing Cu Minerals MoConcentrate Cu Concentrate u 0 Cu Mo Cu Mo 485-299--- 2-11 and 2-200 8:}11. 0 97.1 57.3 "Nokes" reagent .Q 4.7 44.0 92.4 13.3 485-292-.- Z-11and 2-200 }11.5 95.5 55.4 Sodium Ierrocyanide and heat 8.5 46.8 87.0 9.6485-307- Nitrogen distillate 0.138 7.7 93.9 92.3 Sodium sulfide 4.4 82.589.5 9.8 d 0 115 7. 9 93.4 90. 6 Sodium hydroxide and heat 9. 7 77.4 83.7 13. 2 91. 2 88. 9 Potassium permanganate l2. 9 78. 4 78. 3 10. 5 92. 192.6 Nokes reagent 3. 4 52. 4 89.7 40. 2 93. 2 92.0 sodigrtl1fterrocyanide, sodium hydroxide, 4. 1 53. 7 89. 1 38. 3

an ea.

Example VI shows the effect of using nitrogen distillate in testing as abulk collector followed by depression tests using Nokes reagent andother depressants.

It will be noted that nitrogen distillate consistently floats moremolybdenum minerals and that much better recovery of molybdenum isobtained in the resulting molybdenum concentrates in all of thedepressant tests.

The laboratory examples noted above show that NBC oil is a multi-purposereagent, both a bulk flotation collector by itself, a synergisticauxiliary reagent to the traditional sulfhydryl collectors (anionics)and isothiouronium salts (cationics), is a good copper collector with atendency to depress pyrite on both copper and coppermolybdenum sulfideores, is a good molybdenum collector on ores containing only molybdenumsulfide, and is also a froth modifier for the isothiouronium salts.

In the operations where both molybdenum and copper concentrates werecollected through the use of the S-substituted isothiouronium salts andNBC oil, it was found that the use of sodium ferrocyanide as adepressant for the copper sulfide minerals was unusually eifective,giving greater filterability of the molybdenum minerals and also of thecopper minerals.

While in the foregoing specification we have set forth specificprocedure in considerable detail for the purpose of illustratingembodiments of the invention, it will be understood that such details ofprocedure may be varied widely by those skilled in the art withoutdeparting from the spirit of our invention.

heterocyclic nitrogen compounds extracted from the mineral gilsonite andhaving an average boiling point :within the range of about 200 F. to 750F., and separating molybdenum and copper concentrate as froth product.

6. The process of claim 5 in which said conditioning with saidheterocyclic nitrogen compound mixture is carried out in the presence ofan auxiliary collector selected from the group consisting of alkyl andaryl dithiophosphates, dithiocarbonates, dithiocarbamates,thionocarbamates, thioureas, and xanthogen for-mates.

References Cited HARRY B. THORNTON, Primary Examiner.

R. HALPER, Assistant Examiner.

